Keywords: Herschel kyanotypie pozitiv.jpg en An experimental cyanotype of an engraving of a lady with a harp by Sir John Herschel 1792-1871 1842 Herschel invented the cyanotype or 'blueprint' in 1842 employing iron salts ferric ammonium citrate and potassium ferricyanide which produce Prussian blue under the action of light It was a simple process to use and required only water as a fixative The cyanotype was the only first-generation photographic technique to find any lasting use cs Žena s harfou snímek zhotovený Herschelem v roce 1842 metodou kyanotypie - pozitiv http //www mhs ox ac uk/features/ephotos/nphoto5 htm photo John Herschel 1842 PD-old John Herschel |